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>>> Russ Smith <hysave@fta.com> 03/07/97 05:24am >>>
The question posed:
> There are a variety of parameters to control ventilation: CFM per
person,
> Air Changes, CO2, and RH. If you had to pick one, which one would
you pick
> and why?
> Greg Thomas
I found these questions to be of interest so I asked one of our
distributors if he could contribute from his experience.
The following are his thoughts on the subject:
From:
SLGHVAC@aol.com
To:
hysave@fta.com
CO2 level is the most accurate means of controlling the need for outside
air.
EPA requires level to be less than 1,000 ppm and I understand that that
may be dropped to 800 ppm very soon. If a fixed cfm/person is used to
bring in fresh air, the maximum amount of air will be introduced weather
the max or min amount of people are inside the building. By monitoring
CO2 levels inside and having C02 sensors controll outdoor air dampers,
the amount of fresh air will be introdced in proportion to the internal
ventilation demand.
This is called demand controlled ventilation DCM, and is used primarily
with direct digital control DDC systems that are able to accurately
control dampers based on sensor signgals.
Energy can be saved by only bringing in the amount of outdoor air
necessary at any particular time.
Thanks for the question.
Scott
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__________________________________________________________________
__________________________________________________________________
This greenbuilding dialogue is sponsored by Oikos (www.oikos.com)
and Environmental Building News (www.ebuild.com). For instructions
send e-mail to greenbuilding-request@crest.org.
__________________________________________________________________